#include <bits/stdc++.h>
using namespace std;
#define ll long long
int tt, tc;

void solve() {
    int h, w;
	cin >> h >> w;
	vector<string> v(h);
	for (auto& u : v) cin >> u;

	vector<char> imp = { 'W', 'A', 'L', 'D', 'O' };
	int sq = sqrt(h * w) + 5;
	ll ans = 1e18;

	{
		vector<vector<vector<int>>> nxt(5, vector<vector<int>>(h, vector<int>(w, w)));
		for (int k = 0; k < 5; k++)
			for (int i = 0; i < h; i++) 
				for (int j = w - 2; j >= 0; --j) nxt[k][i][j] = (v[i][j + 1] == imp[k] ? j + 1 : nxt[k][i][j + 1]); 

		auto find_height = [&](int row, int col, int k) {
			if (v[row][col] == imp[k]) return 1LL;
			if (nxt[k][row][col] == w) return (ll)1e15;
			return nxt[k][row][col] - col + 1LL;
		};
		
		for (int col = 0; col < w; col++) {
			for (int len = 1; len <= min(h, sq); len++) {
				vector<set<pair<ll, int>>> x(5);
				for (int k = 0; k < 5; k++) 
					for (int row = 0; row < len; row++) 
						x[k].emplace(find_height(row, col, k), row);
				auto find_min = [&]() {
					ll mx = -1e18;
					for (int k = 0; k < 5; k++) mx = max(mx, x[k].begin()->first);
					return mx;
				};
				ans = min(ans, len * find_min());
				for (int row = len; row < h; row++) {
					for (int k = 0; k < 5; k++) x[k].erase(make_pair(find_height(row - len, col, k), row - len));
					for (int k = 0; k < 5; k++) x[k].emplace(find_height(row, col, k), row);
					ans = min(ans, len * find_min());
				}
			}
		}
	}

	vector<string> new_v(w);
	for (int i = 0; i < h; i++)
		for (int j = 0; j < w; j++)
			new_v[j].push_back(v[i][j]);
	swap(h, w);
	v = new_v;

	{
		vector<vector<vector<int>>> nxt(5, vector<vector<int>>(h, vector<int>(w, w)));
		for (int k = 0; k < 5; k++)
			for (int i = 0; i < h; i++) 
				for (int j = w - 2; j >= 0; --j) nxt[k][i][j] = (v[i][j + 1] == imp[k] ? j + 1 : nxt[k][i][j + 1]); 

		auto find_height = [&](int row, int col, int k) {
			if (v[row][col] == imp[k]) return 1LL;
			if (nxt[k][row][col] == w) return (ll)1e15;
			return nxt[k][row][col] - col + 1LL;
		};
		
		for (int col = 0; col < w; col++) {
			for (int len = 1; len <= min(h, sq); len++) {
				vector<deque<int>> x(5);
				auto add = [&](int k, int new_row) {
					while (!x[k].empty() && find_height(x[k].back(), col, k) > find_height(new_row, col, k)) 
						x[k].pop_back();
					x[k].push_back(new_row);
				};
				for (int k = 0; k < 5; k++) 
					for (int row = 0; row < len; row++) 
						add(k, row);
				auto find_min = [&]() {
					ll mx = -1e18;
					for (int k = 0; k < 5; k++) mx = max(mx, find_height(x[k].front(), col, k));
					return mx;
				};

				ans = min(ans, len * find_min());
				for (int row = len; row < h; row++) {
					for (int k = 0; k < 5; k++) if (x[k].front() <= row - len) x[k].pop_front();
					for (int k = 0; k < 5; k++) add(k, row);
					ans = min(ans, len * find_min());
				}
			}
		}
	}

	cout << (ans <= h * w ? to_string(ans) : "impossible") << "\n";
}

int main() {
    ios::sync_with_stdio(0); cin.tie(0);
    tt = 1, tc = 1; // cin >> tt;
    while (tt--) solve(), tc++;
}